I’ve gone through several Timex Triathlons over the years, several of them falling prey to busted buttons, and I did not care at all for some of the subtle changes made after my first model. In particular, the chronometer used to beep upon being reset, but now it doesn’t, and thus you actually need to look at the watch to determine if you’ve held down the reset button for long enough so you can start up the chronometer again. A small change, but a frustrating one – and sadly, any such subtle changes to the watch circuitry are probably well beyond what a hobbyist could accomplish.

My favorite model is the Casio DB36-1AV. It’s the Databank version without the calculator. I particularly like it because it has an agenda/calendar functionality, you can save contacts with phone numbers and emails, and then the other standard Casio features. I found it infinitely useful, i don’t have one any more but i’ve mulled over getting one in case i ever lose my cellphone i would be able to have some saved numbers to reach out to people with. It’s super affordable at less than 20 bucks.

The unmodded version, while not billed as waterproof, has survived plenty of water time with me. I used to go swimming with it and I even took it into the ocean a few times. Never more then a meter below the surface though.

(Norton used to claim that they could make a bike that did not leak oil, but that it was a valuable feature because it ensured owners would check the oil level and not fail to replace it when needed. Yes, sure.)

It’s not a smartwatch, this model has been around for quite some time (mine was bought in the 90’s) so unfortunately there’s no import/export features. It’s all handled by the user manually inputting contacts and other entries. It’s a little bit of a hassle but i always found the contact bit to be very useful, you never know when you won’t have your phone accessible.

However i do wonder if it could be hacked to ease the method of inputting data and maybe even exporting/importing it.

I don’t know enough about hardware hacking and coding to make an educated guess but the stock databank watch doesn’t have any ports so you’d have to hack one on maybe. If it’s possible it’d be a neat project for someone.

Filling with oil is for water resistance to extreme depths - up to 10,000m (vs. most dive watches, which are 200m). If you eliminate the air inside the watch, it won’t compress under pressure. The trick is that you need a bladder to allow the oil to expand and contract a little with temperature and pressure changes - otherwise, it’ll leak oil

Sorry I thought this was one which interfaced to a computer through the screen, ie, you run an app on the computer, enter your data, enter a transfer mode, then pulses on your screen upload data to the device.

So maybe this is a servo application. Looks like it only has six buttons. I have a microcontroller board which directly drives eight aeromodellng servos. I have a different board which interfaces to a raspberry pi through a serial interface. All the bits are there. Just code a sequence which will upload your data through the buttons.

Presumably the watch has a function to delete all data. The servos would start there then do a fresh load when the data changes.